[shamanNS]

"One True Page Number" is obviously based on number of characters, where that number is relatively close to the average / typical paperback pBook What should constitute that typical definition should be one time decision when used start generating that info.

Personally I like having the ability to have a both "dynamic count" (= number of screens, dependent on chosen formatting settings) and "static count" ( = this is an idea how pbook page count would be like) and KOReader enables me to have that. With an "user patch" that for epubs that don't have PageMap/PageList information ( that maps to a particular pBook edition) makes / fakes "Reference pages numbers list" with the criteria being X number of characters, where I choose that X.

local ReaderPageMap = require("apps/reader/modules/readerpagemap")
local postInit_orig = ReaderPageMap._postInit

ReaderPageMap._postInit = function(self)
    self.ui.document:buildSyntheticPageMapIfNoneDocumentProvided(1650)

    -- Run original code
    postInit_orig(self)
end

So I always have a choice whether I want to have both types of counts (faked pbook pages or actual number of screens) displayed at the same time or choose which of the two should be used for progress bar indicator.

Even if I don't actually change formatting option between different books and have a clear an fairly constant formula that screen count + 30-to-35% = "typical" pbook count... I still like tl have that information visually.